Two identical pieces of rectangular plate glass are used to measure the thickness of a hair. The glass plates are in direct contact at one edge and a single hair is placed between them hear the opposite edge. When illuminated with a sodium lamp \((\lambda=589 \mathrm{~nm})\), the hair is seen between the 180th and 181st dark fringes. What are the lower and upper limits on the hair’s diameter?
Text Transcription:
lambda=589 nm
iClicker What is an electric flux through spheres of radii r1 and r2 e e A :Φ 1 − , Φ2= 0 0 e B :Φ = − e , Φ =0 1 0 2 r2 -e e C :Φ 10 , Φ = 2 r1 0 e D :Φ 10 , Φ = 2 0 E :Φ = e , Φ = − e 1 0 2 0 1 iClicker What is an electric flux through spheres of radii r1 and r2 e e A :Φ 1 − , Φ2= 0 0 e B :Φ = − e , Φ =0 1 0 2 r2 -e e C :Φ 10 , Φ = 2 r1 0 e D :Φ 10 , Φ = 2 0 E :Φ = e , Φ = − e 1 0 2 0 2 Continuous Distribution of charges Two methods: •Method #1: Divide the distribut+on + E into infinitesimal elements dE an+ + integrate to get the full electric field + •Method #2: If there is some special dq symmetry of the distribution, usE = k ˆ Gauss’ Law to derive the field from r2 46 Simple
